Electric system



June-22, 1937. H. GEISE 2,084,904

ELECTRIC SYSTEM Filed May 19, 1936 Inventor: Hermann Geise.

tbor 'r ey Patented June 22, 1937 ELECTRIC SYSTEM Hermann Geise,Berlin-Karlshorst, Germany, assignor to General Electric Gompany, acorporation of New York Application May 19, 1936, Serial No. 80,632 InGermany May 28, 1935 7 Claims.

My invention relates to electric systems wherein power is transferredbetween alternating current and direct current circuits by vaporelectric apparatus such as mercury arc rectifiers or the like. Theinvention relates particularly to systems of this character in which thevoltage is regulated by means of grids or control electrodes, and theobject of the invention is to provide capacitance means so arranged asto eliminate 10 completely in the system. radio frequency oscilablenoise in broadcasting radio receivers.

lations tending to disturb radio reception.

It is known that in the operation of mercury arc rectifier systems,disturbing radio frequency oscillations are produced which causeconsider- These disturbances are of particularly large magnitude in casethe voltage in the rectifier apparatus be regulated with the aid ofgrids or control electrodes. In the operation of the grid control meansthe initiation of the successive arcs between the anodes and the cathodeis delayed, so that at each initiation of the anode current the voltagerises abruptly and irregularly, with the effect of generating highfrequency oscillations which decay comparatively rapidly, to occur againupon the initiation of current at the next succeeding anode. A high, orradio, frequency is thereby produced which is modulated in accordancewith the successive initiations of current at the anodes and which,because of the rectification occurring in the broadcasting receivingapparatus, becomes audible as a tone in the latter apparatus. In thecase of six-phase rectifiers the disturbing tone has for the most part afrequency of 300 cycles per second and in the case of twelve-phaserectifiers, a frequency of 600 cycles per second.

In order to eliminate the disturbing high frequency oscillations,condensers have been provided heretofore, between the anodes and thecathode in rectifiers without grid control. It has been possible, as ageneral rule, to obtain satisfactory results by these simple means sincethe disturbances were mainly due to the fact that the anodes were merelynot conducting current quite regularly, and the disturbances, from thiscause, were consequently not particularly noticeable. In the case ofgrid controlled rectifiers, however, this remedial measure is by nomeans sufficient.

By means'of the circuit organization in ac cordance with my presentinvention it is possible to diminish the disturbing radio frequencyoscillations to such a degree that highly sensitive broadcastlong-distance receivers will operate free from these disturbances, evenin proximity to rectifier equipment.

The chief feature of this circuit arrangement is that all of the leadsand conductors brought into the rectifier tank or metal container arecapacitatively interconnected and are furthermore capacitively grounded.This result may be effected for example, in this manner, that the mainanodes, grids, and the auxiliary or excita tion anodes are connectedthrough condensers with the cathode or with ground, or with therectifier casing which is either directly or capacitatively grounded. Bythe term rectifier casing it is to be here understood that in the caseof iron rectifiers the iron tank or shell is meant, and in the case ofglass rectifiers, the sheet metal casing or box surrounding the glassbulb.

Furthermore, the cathode must likewise be grounded through a condenser,or must be connected to the directly or capacitatively groundedrectifier casing. What is of particular importance is the manner inwhich the capacitative connection of the cathode with ground is made.This capacitative connection between cathode and ground should be madedirectly at the cathode, if possible, and in any case not at a point,along the positive conductor, far away from the cathode.

It has been found, further, to be advantageous to connect the neutralpoint of the transformer, which supplies the anode voltage, directlywith the transformer casing or shell by way of a condenser. Theeffectiveness of the latter connection will be further enhanced by acapacitative connection of the positive and negative terminals of therectifier apparatus with ground, and at the point where the conductorsconnected to these terminals leave the rectifier equipment and passover, through the building enclosing the apparatus, into thedistributing network constituted by cable or air lines.

Since it may happen that radio frequency oscillations pass over from therectifier apparatus into the three-phase or other alternating currentsupply network, all of the anode terminals of the transformer may beconnected by way of condensers to the transformer casing or shell.

My invention will be better understood from the following descriptionwhen. considered in connection with the accompanying drawing and itsscope will be set forth in the appended claims.

Referring to the drawing, the single figure thereof is a diagrammaticrepresentation of a mercury arc rectifier system in which my inventionhas been embodied.

In the drawing the numerals I and. 2 designate respectively analternating current circuit and a direct current circuit between whichpower is transferred by vapor electric equipment comprising atransformer 3, having a primary 4 and a secondary 5, and a rectifierapparatus 6 including a cathode l, main anodes 8, grids or controlelectrodes 3, and excitation or auxiliary anodes iii, the cathode,anodes, and grids being enclosed within a casing or container Ii whichin the present embodiment of the invention is a metal tank from whichthe cathode I is insulated by an insulating member !2.

The windings of transformer 3 are enclosed within a metal casing l3through the walls of which extend conductors i l connecting the phaseterminals iii of the transformer secondary 5 with the correspondinganodes 8. The grids 9 are connected through leads iii to suitable gridexcitation means il (not shown), and the excitation anodes iii areconnected through leads i8 to an excitation transformer l9 supplied froma suitable source Ell (not shown). A positive direct-current conductor2i, connected to cathode l, and a negative direct-current conductor 22,connected to neutral point 23 of transformer secondary 5, connect therectifying equipment to the directcurrent circuit 2 through a wall of abuilding 2 which may enclose the complete equipment.

In accordance with my invention, leads i l con nected to anodes 8, leadsl6 connected to grids 9, and leads l8 connected to excitation anodes Ii]are all capacitatively interconnected, and all capacitatively grounded,by condensers 25 and lead 28 between main anode leads 8 and cathode '6,condensers 2'! and lead 28 between grid leads l6 and the cathode, andcondensers 2% and leads 3!! between excitation anode leads I8 and thecathode, the cathode i being capacitatively connected to the groundedrectifier casing I I through a con denser 3!.

Further, in accordance with my invention, the neutral point 23 oftransformer secondary 5 is capacitatively connected by a condenser 32and a lead 33 with the grounded transformer casing or shell l3, and thephase terminals l5 of secondary 5 are capacitatively connected bycondensers 34 and leads 3'5 with the grounded casing 53. Finally, inaccordance with my invention, the two conductors 2! and 22 carryingdirect current are capacitatively grounded by condensers 36 mountedclosely adjacent to the point at which the latter conductors pass fromthe enclosing building 24.

My invention has been described herein in a particular embodiment forpurposes of illustration. It is to be understood, however, that theinvention is susceptible of various changes and modifications and thatby the appended claims I intend to cover any such modifications as fallwithin the true spirit and scope of my invention.

What I claim as new and desire to secure by Letters Patent of the UnitedStates is:

1. In an electric system comprising an alternating current circuit, adirect current circuit, and means to transfer power between saidcircuits including a vapor electric apparatus having a cathode and atleast one anode and a control electrode associated with said anode, anda plurality of leads connected respectively to said cathode, said anodeand said control electrode, means to eliminate in said system radiofrequency oscillations tending to disturb radio reception, saidlastnamed means including capacitance means inter-- connecting all ofsaid leads and connecting all of said leads to ground.

2. In an electric system comprising an alternating current circuit, adirect current circuit,

and means to transfer power between said circuits including a vaporelectric apparatus having a metal casing enclosing a cathode and aplurality of anodes and control electrodes, and a plurality of leadsconnected respectively to said cathode, said anodes, and said controlelectrodes, means to eliminate in said system radio frequencyoscillations tending to disturb radio reception, said lastnamed meansincluding capacitance means interconnecting all of said leads andconnecting all of said leads to ground.

3. In an electric system comprising an alternating current circuit, adirect current circuit, and means to transfer power between saidcircuits including a transformer, a metal casing enclosing saidtransformer, a vapor electric apparatus including a metal casingenclosing a cathode and a plurality of anodes and control electrodes,and a plurality of leads connected respectively to said cathode, saidanodes, and said control electrodes, means to eliminate in said systemradio frequency oscillations tending to disturb radio reception, saidlast-named means including capacitance means interconnecting all of saidleads and connecting all of said leads to ground and capacitance meansconnecting the neutral point of said transformer to said transformercasing.

4. In an electric system comprising an alternating current circuit, adirect current circuit, and means to transfer power between saidcircuits including a vapor electric apparatus having a metal casingenclosing a cathode and a plurality of anodes and control electrodes,and a plurality of leads connected respectively to said cathode, saidanodes, and said control electrodes, a building enclosing said apparatusand said leads, and a positive lead and a negative lead connecting saidapparatus through said building to said direct current circuit, means toeliminate in said system radio frequency oscillations tending to disturbradio reception, said lastnamed means including capacitance meansinterconnecting all of said first-named leads and connecting all of saidfirst-named leads to ground,

\ and capacitance means connecting said positive and negative leads toground closely adjacent the point at which said last-named leads passfrom said building.

5. In an electric system comprising an alternating current circuit, adirect current circuit, and means to transfer power between saidcircuits including a transformer a metal casing enclosing saidtransformer, a vapor electric apparatus including a metal casingenclosing a cathode and a plurality of anodes and control electrodes,and a plurality of leads connected respectively to said cathode, saidanodes, and said control electrodes, a building enclosing saidtransformer casing and said apparatus and leads, and a positive lead anda negative lead connecting said apparatus through said building to saiddirect current circuit, means to eliminate in said system radiofrequency oscillations tending to disturb radio reception, said lastnamed means including capacitance means interconnecting all of saidfirst-named leads and connecting all of said firstnamed leads to ground,capacitance means connecting the neutral point of said transformer tosaid transformer casing, and capacitance means connecting said positiveand negative leads to ground closely adjacent the point at which saidlast-named leads pass from said building.

6. In an electric system comprising a direct current circuit, analternating current circuit,

and means to transfer power between said circuits including a vaporelectric apparatus having a metal casing enclosing a cathode and aplurality of anodes and control electrodes, a transformer having aplurality of terminals connected respectively to different ones of saidanodes, a metal casing enclosing a transformer, and a plurality of leadsconnected respectively to said cathode, said anodes, and said controlelectrodes, means to eliminate in said system radio frequencyoscillations tending to disturb radio reception, said last-named meansincluding capacitance means interconnecting all of said leads andconnecting all of said leads to ground and capacitance means connectingthe neutral point of said transformer and said anode terminals of saidtransformer to said transformer casing.

'7. In an electric system comprising a direct current circuit, analternating current circuit, and means to transfer power between saidcircuits including a vapor electric apparatus having a metal casingenclosing a cathode and a plurality of anodes and control electrodes, atransformer having a plurality of terminals connected respectively todifferent ones of said anodes, a metal casing enclosing saidtransformer, a building enclosing said transformer casing and saidapparatus and said leads, and a positive lead and a negative leadconnecting said apparatus through said building to said direct currentcircuit, means to eliminate in said system radio frequency oscillationstending to disturb radio reception, said last-named means includingcapacitance means interconnecting all of said firstnamed leads andconnecting all of said first named leads to ground, capacitance meansconnecting said positive and negative leads to ground closely adjacentthe point at which said lastnamed leads pass from said building, andcapacitance means connecting the neutral point of said transformer andsaid anode terminals of said transformer to said transformer casing.

HERMANN GEISE.

